I have a very bad theory about everything.
Lord Ku and Ohnoki are not creating the Akuta out of nowhere, they require actual souls and the reason they need Mitsuki is because he is a hybrid clone between Zetsu and Toneri DNA. Basically throwing in the Zetsu cause it would be similar to the Akuta. The big WTF reveal of this whole arc is that this all started out after they tried to bring back Kozuchi but instead found a really fucked up defense mechanism for their Village. And to top it all off, Kozuchi=Akkun.
OHHHH MY GOOOD THE AKUTA BETTER NOT BE HIS GRANDSON I'LL SHIT YO